build.children
returns a named list of vectors. Each component corresponds to a node \(x\) of the graph and its
vector is the set of its children
get.children.top.down
returns a named list of character vectors. Each component corresponds to a node \(x\)
of the graph (i.e. parent node) and its vector is the set of its children. The nodes are ordered from root (included) to leaves.
get.children.bottom.up
returns a named list of character vectors. Each component corresponds to a node \(x\)
of the graph (i.e. parent node) and its vector is the set of its children. The nodes are ordered from leaves (included) to root.